[134] It is not
necessary for understanding the relationship of launch vehicles to
the space science program to delve deeply into how they were
developed, but a few principles should be understood. First, a
number of different vehicles were required. One might have
supposed that a single launch vehicle, which could do everything
the program required, would be ideal. With only one manufacturing
line, one kind of assembly, test, and launch facilities, one kind
of operational equipment and procedures, and basically
[135] one launch
team, a substantial background of experience would quickly build
up for that vehicle. Engineers and technicians would become
thoroughly familiar with its characteristics and idiosyncrasies,
so that a high degree of reliability could be ensured.

But in an era when a launch vehicle was
expended for each firing, the economics would not be favorable.
For, to be acceptable, a single vehicle would have to be able to
accomplish both the simplest and the most difficult of the
missions required-from small, near-earth satellite missions to
manned flights to the moon. On the most difficult missions, the
launch vehicle would presumably operate most efficiently, and the
costs would be commensurate with the accomplishments. But to use
such a vehicle for less demanding missions would be most
inefficient; indeed, the cost of the launch vehicle could
overwhelm the cost of the spacecraft. To mitigate this problem of
cost there would, of course, be pressure to fly many small
missions on a single launch vehicle, or to let small missions ride
piggyback on larger ones, thus, reducing the cost per spacecraft;
but then different kinds of complications would enter in. Some of
these would be fundamental, as when one set of experiments
required a circular orbit, another set an eccentric orbit, still
another a polar orbit, and a fourth an equatorial orbit.

For expendable launch vehicles such
considerations led to the conclusion that the most efficient
approach would be a graduated series running from a small,
inexpensive vehicle to the very large, very expensive ones. The
gradation between vehicles would be large enough to yield a
substantial increase in payload and mission capability, but small
enough to avoid having to use vehicles too costly for their
assigned missions. Obviously the way in which these requirements
were met was a matter of judgment, and in some respects arbitrary.
The subject was constantly under study by both the military and
NASA.8

Second, the basic physics of rockets
dictated that major launch vehicles should be multistage, or step,
rockets-that is, combinations of two or more rockets, called
stages, which burn one after the other. As soon as the first stage
has used its propellants, it is discarded, after which at an
appropriate time the second stage is ignited. When the second
stage has burned out and been discarded, the third stage is ready
to fire. And so on. Multistaging is important for rockets that
must work against the force of gravity, for otherwise the
propellants must supply the energy needed to propel the entire
rocket structure against the pull of gravity for the whole
launching phase. But with staging, in which portions of the
structure are discarded as soon as they are no longer needed, only
a small fraction of the entire vehicle need be propelled into the
final orbit or space trajectory. The early rocket pioneers
recognized the importance of staging, a point that Robert Goddard
elaborated in his famous Smithsonian paper.9 In the space program two-stage and three-stage
vehicles became common, four-and five-stage combinations not
uncommon.

[136] In the
scramble to put together a national launch vehicle capability
after the formation of NASA, it was natural that whatever vehicles
were available or could be assembled from the existing military
programs would be used. In 1959 six out of the seven vehicles that
were available to NASA came largely from the missile
program.10 The seventh was Vanguard, which had been built by
the Navy for the IGY.

To expand the national capability,
additional vehicles would be developed (fig. 10). Scout, a four-stage, solid-propellant vehicle,
would provide an inexpensive means for launching 70 kilograms to
185 (or even 550) kilometers. Vega and Centaur, the latter using
the high-energy propellants liquid hydrogen and liquid oxygen,
would substantially extend the launch capability of Atlas-based
vehicles. Juno V vehicles and Nova were intended to support a
variety of manned missions. Nova was expected to generate a thrust
of 6000000 pounds-almost 27,000,000 newtons-and would be required
for launching men in a direct ascent from the ground to the
moon's- surface.

Fifteen years later the situation was
entirely different. By then a bewildering variety of rocket stages
and launch vehicle combinations had been developed, along with an
extensive literature.11 What the vehicles could do for the various Space
missions can be deduced from the performance figures for the
launch vehicles in figures 10 through 14.

As seen in figure 11, by 1962 the Hustler and Vega had been eliminated.
Likewise, Juno II, which had not proved particularly useful, had
beer dropped. Nova plans called for doubled thrust, and Saturn was
to rely on liquid-hydrogen, liquid-oxygen engines for its upper
stages. By 1966 Now had disappeared because of NASA's decision in
July 1962 to use lunar-orbit rendezvous instead of direct ascent
for the Apollo missions.12 Several versions of Saturn would support NASA's
manned spaceflight programs; the largest, Saturn V, would be used
for the manned lunar missions.13 The Department of Defense preferred not to be tied
into the expensive and highly experimental Saturn, so in following
years the Titan III line of launchers was introduced into the
stable to support large-scale military missions. Titan III
additions can be seen in the display for 1972 (fig. 13), at which time the only Thor-based vehicle
remaining was Delta.

These launch vehicles, with the sounding
rockets discussed at the start of this chapter, made up the
backbone of U.S. capability to explore and investigate space. They
resulted from joint planning by NASA and the military to serve
their respective needs.14 Other rockets and rocket stages were put together
for special purposes, usually by the military, but their existence
did not change the overall picture.

In the 1970s a basic change was initiated
with the commitment to the Space Shuttle, which in the 1980s would
supplant most of the expendable boosters for launching spacecraft
into near-earth orbit. The launch vehicle line-up in the fall of
1976 (fig.
14) shows how the elimination of
the [137] Saturns, following the completion of the
Apollo and Skylab programs by the mid-1970s, and the prospect of
the Space Shuttle by the 1980s had thinned out the stable. Only
five vehicles remained: Scout for small payloads, Delta and
Atlas-Centaur for medium and large payloads, and two Titan III
combinations for the very large payloads.

Throughout the entire evolution of the
launch vehicle stable, both Scout and Delta remained. Relatively
inexpensive, able to support a substantial number of the
researches that scientists wanted to do, these launch vehicles had
great appeal. Even with the Shuttle in operation, Scout at least
was likely to remain, for even the Shuttle might not prove
economical for small missions with a wide variety of special
trajectory requirements.

Scout and Delta also illustrate another
feature of the national launch vehicle program. As the group of
vehicles improved as a family over the years, performance of the
individual vehicles also improved. In 1962 Scout could put 100 kg
into a near-earth orbit; by the 1970s this performance had
doubled. In the same period Delta's performance had shown an even
greater growth. In 1962 Delta could send several hundred kilograms
into a near-earth orbit or 25 kg to Mars or Venus; by 1976 Delta
could loft 2000 kg into a 185-km orbit or 340 kg to the near
planets. The increased performance, which most vehicles
experienced over the years, was brought by continuing programs of
improving and uprating the vehicles. While improvement programs
were the pride of the vehicle engineers, they were sometimes the
bane of top management, which would often have preferred to settle
upon some acceptable level of performance and then stop spending
any more money on vehicle development.

Like the United States, the Soviet Union
developed a launch vehicle stable.15 During the 1960s, however, the Soviet Union
appeared to rely on fewer kinds of vehicles than did the United
States, preferring to use a single model for a wider variety of
missions. The Russian preference may be prima facie evidence that
the economic factors of using large vehicles for small-payload
missions were not as prohibitive as American planners felt they
were; but comparing Russian economics with American is a risky
business. The USSR may simply have decided to pay the extra cost
for the convenience afforded.

Only the United States and the Soviet
Union developed extensive launch capabilities. Other nations
interested in space research and applications turned largely to
the United States for assistance in launching spacecraft or
individual experiments, as will be explored in chapter 18. Some nations, however, desiring to lessen this
dependence, proceeded to develop vehicles of their own. Among
those were Britain, France, Japan, People's Republic of China, and
the European Launcher Development Organization, a coalition of
countries that pooled resources to develop a launcher approaching
the Atlas-Agena capability.16 Italy set up an equatorial launching facility in
the Indian Ocean off the coast of Kenya, but used the American
Scout as launch vehicle.17

[140] By
1966-when Centaur became fully operational-the United States could
at last launch spacecraft for just about any space mission the
country might want to undertake, except the very demanding ones
requiring the Saturn or Titan still under development. Although
the debate over whether the United States could or could not match
Russian launch capability still arose occasionally, the subject no
longer had the importance it once did. As long as the United
States could carry out the scientific investigations and make the
space applications it desired-sometimes using miniaturization
techniques to overcome limitations on total payload weights-the
country could compete with the Soviet Union on essentially equal
terms, and the comparative sizes of rockets were then an
artificial criterion on which to judge Soviet and U.S. space
prowess.

The ability to launch objects and men into
space rested on a substantial investment in manpower and
facilities-design, engineering, construction, assembly, and test
facilities in both industry and government. Most visible were the
launching ranges, which along with the launch vehicles themselves
symbolized. the nation's space capability. In the United States
the principal facilities were the Eastern Test Range, with launch
areas at Cape Canaveral and Merritt Island in Florida; and the
Western Test Range, for which the launching areas were at
Vandenberg Air Force Base in California.18 A smaller launch station was used by NASA for
firing Scouts from Wallops Island on the Virginia
coast.19 Supplementing these were sounding rocket ranges at
the White Sands Missile Test Facility in New Mexico, Wallops
Island, Point Mugu in California, and Fort Churchill in northern
Canada. Occasionally shipborne launchers were used for special
missions.

The Soviet Union operated a number of
major launch ranges out of Tyuratam, Kapustin Yar, and
Plesetzk.20 A few other countries established satellite launch
ranges.21 By invitation American sounding rockets were fired
at numerous ranges around the world-for example, at Thumba in
India, at Woomera in Australia, and at Andoeya,
Norway.22